In modem office buildings, business and conference centers, hotels, classrooms, medical facilities, and the like, the fitting-out of occupiable space is continuously becoming more important and ever more challenging. In the competitive business environment, cost concerns alone dictate the efficient use of interior space. Thus, the finishing or fitting-out of building spaces for offices, hotel rooms, and similar areas has become a very important aspect of effective space planning and layout. Among many factors that designers and builders must consider is sound control. In hotels, for example, the prevention of sounds originating in one room from passing through walls and into adjacent rooms is of major concern.
Sound transmission through walls is typically expressed according to one of two single-number rating systems—Sound Transmission Class (STC) and Weighted Sound Reduction Index (Rw). Both are single-figure ratings schemes intended to rate the acoustical performance of a partition element under typical conditions involving office or dwelling separation. The higher the value of either rating, the better the sound insulation. The rating is intended to correlate with subjective impressions of the sound insulation provided against the sound of speech, radio, television, music, office machines and similar sources of sound characteristic of offices and dwellings.
The first rating system is called Sound Transmission Class (STC). STC is defined by the American Society for Testing Materials (ASTM) standard E 413. To assign an STC rating to a barrier separating two rooms, a sound is generated in one of the rooms, the sound power is measured on both sides of the barrier, and the ratio between the two measurements (the transmission loss) is stated in decibels. Sixteen measurements are made in each room, at ⅓ octave intervals from 125 HZ to 4000 HZ. The higher the STC rating, the greater the sound transmission loss. The E413 standard specifies a transmission loss curve having 16 points on the same ⅓ octave intervals. From 125 to 400 Hz, the curve slopes upward, 9 dB per octave; from 400 Hz to 1250 Hz, upward 3 dB per octave, and it is flat from 1250 Hz to 4000 Hz. The curve is moved up and down until the sum of all 16 differences between the curve values is a minimum. The Minimum must be less than 32 dB, providing no single difference is more than 8 dB. The rating is then expressed as the curve's loss in decibels at 500 Hz.
The second rating system is called Weighted Sound Reduction Index (“Rw”) and is defined by International Standards Organization standard ISO 717. Test procedure for Rw are similar to STC except the frequency range for Rw spans 100–3150 HZ whereas, as indicated supra, STC covers a frequency range of 125–4000 Hz. STC and Rw correlate very well. For architectural elements such as doors, windows and walls, differences in STC and Rw are typically less than 1%.
Interior walls in offices, hotels and the like are typically made by erecting a frame that includes vertical studs, either wood or steel, on a 12″ or 16″ spacing, lining each side with gypsum board (sheet rock) panels, then finishing the wall surfaces with a variety of textures and paint. When additional thermal and/or acoustic insulation is needed, insulation medium such as fiberglass, rock wool or mineral wool will commonly be placed to fill the interior space between vertical studs and gypsum board panels. FIGS. 1a–1d illustrate a cross-sectional top-down view of such constructions.
FIG. 1(a) shows prior art wall construction (100) comprised of vertical 2×4 studs (102) lined on each side by ⅝″ gypsum board (101), with an air space (103) in between. The wall construction of FIG. 1a will typically have a Rw value of 33 and will be ˜4¾″ wide between exterior surfaces.
FIG. 1(b) shows prior art wall construction (200) comprised of vertical 2×4 studs (202) lined on each side by ⅝″ gypsum board (201) with insulation (203) filling the interior space. The wall construction of FIG. 1(b) will typically have a Rw value of 38 and will be ˜4¾″ wide between exterior surfaces.
FIG. 1(c) shows prior art wall construction (300) comprised of 3⅝″ vertical steel studs (302) lined on each side by ⅝″ gypsum board (301) with air space (303) in between. The wall construction of FIG. 1(c) will typically have a Rw value of 33 and will be ˜4⅞″ ½″ wide between exterior surfaces.
FIG. 1(d) shows prior art wall construction (400) comprised of 3⅝″ vertical steel studs (402) lined on each side by ⅝″ gypsum board 401 with insulation (403) filling the interior space. The wall construction of FIG. 1(d) will typically have a Rw value of 40 and will be ˜4⅞″ wide between exterior surfaces.
These conventional walls have proven over time to be sturdy, provide adequate privacy, and provide a surface that easily accepts wall hangings such as pictures, paintings, plaques and the like. Furthermore, as is commonly known, conventional walls can easily be repainted, retextured, and, readily patched and repaired when damaged. However, the acoustic properties of walls constructed by this method provide acoustic properties that often do not meet user needs.
To increase the sound attenuating properties of walls, numerous alternative practices have been used FIGS. 1(e)–1(g) provide top-down cross-sectional views of alternative constructions. It can be seen by comparison the FIGS. 1(a)–1(d), the wall constructions shown in FIGS. 1(e)–1(g) each have an overall wall thickness that
FIG. 1(e) shows a prior art wall construction (500) wherein vertical 2×4 studs (502) are placed in a staggered configuration such that no direct rigid connection is made between gypsum board panels (501) lining each wall face. Insulation (503) is used to fill interior spaces. The overall wall thickness of prior art wall construction (500) typically exceeds 6″.
FIG. 1(f) shows a prior art wall construction wherein vertical 2×4 studs (602) are placed in a two-wide configuration effectively doubling the overall wall thickness to ˜9″. Gypsum board (601) lines each face and insulation (603) fills interior spaces.
FIG. 1(g) is similar to FIG. 1(f) except the two-wide 2×4 studs are replaced by 7″ steel studs (702) and two layers of gypsum board (701) are used on one side. Insulation (703) is used to fill interior spaces. The wall constructions illustrated in FIGS. 1(f) and 1(g) are able to provide Rw values of up to 52. The wall construction of FIG. 1(g) has an overall thickness of ˜9″ and, by way of the double layer of gypsum board on one face, provides a one hour fire rating as required by many commercial applications such as hotel constructions.
Due to the ever increasing cost associated with commercial and residential construction and the subsequent need to maximize interior space while minimizing costs, there is a need in the art for economical interior wall constructions that provide both sound attenuating and fire resistance properties while minimizing wall thickness.
Further, since no two applications are identical, the need exists for such a system that provides the versatility to easily customize wall height and width to fit each individual application. The invention disclosed herein meets these needs, as well as providing a wall construction 800 that can be made primarily of recycled materials. The invention disclosed herein represents a significant improvement over existing art.
The compressed straw panels described in the disclosure contained herein, possess structural and acoustical properties very well suited for economically constructing interior walls with superior sound attenuating and fire resistant properties.
For comparison, FIG. 1(h) provides a cross-sectional top-down view of a very simple wall construction that utilizes said compressed straw panel.
FIG. 1(h) shows a 2¼″ compressed straw panel (801) lined on each side by ⅝″ gypsum board (802). Attachment is typically made by means of adhesives and or conventional fasteners such as nails or screws. The wall construction illustrated in FIG. 1(h) has an overall thickness of 3½″ and provides an Rw value of 39.
Lacking in the art are interior wall construction methods that effectively utilize the favorable structural, acoustic and combustion properties of said compressed straw panels, especially the favorable properties achieved when used in concert with resilient channel members that define a space on one or both sides of a compressed straw panel.